Numerous cleanups for snmp_enumusers

* Bring in line with Ruby standards
* More sane format for adding new OSs
* Better logging for use on larger networks
* Better error handling

modules/auxiliary/scanner/snmp/snmp_enumusers.rb

@@ -1,69 +1,76 @@
 ##
-# This module requires Metasploit: http//metasploit.com/download
+# This module requires Metasploit: http://metasploit.com/download
 # Current source: https://github.com/rapid7/metasploit-framework
 ##
 
 require 'msf/core'
 
 class Metasploit3 < Msf::Auxiliary
-
   include Msf::Exploit::Remote::SNMPClient
   include Msf::Auxiliary::Report
   include Msf::Auxiliary::Scanner
+  include SNMP
 
   def initialize
     super(
       'Name'        => 'SNMP Windows Username Enumeration',
-      'Description' => "This module will use LanManager/psProcessUsername OID values to enumerate local user accounts on a Windows/Solaris system via SNMP",
+      'Description' => '
+        This module will use LanManager/psProcessUsername OID values to
+        enumerate local user accounts on a Windows/Solaris system via SNMP
+      ',
       'Author'      => ['tebo[at]attackresearch.com'],
       'License'     => MSF_LICENSE
     )
-
   end
 
   def run_host(ip)
+    peer = "#{ip}:#{rport}"
     begin
       snmp = connect_snmp
 
       sys_desc = snmp.get_value('sysDescr.0')
-      @users = []
-      case sys_desc
-      when /Windows/
-        snmp.walk("1.3.6.1.4.1.77.1.2.25") do |row|
-          row.each { |val| @users << val.value.to_s }
-        end
-      when /Sun/
-        snmp.walk("1.3.6.1.4.1.42.3.12.1.8") do |row|
-          row.each { |val| @users << val.value.to_s }
-        end
-      end
-      unless @users.empty?
-        @users.sort!
-        @users.uniq!
-        print_good("#{ip} Found Users: #{@users.size} users: #{@users.join(', ')}")
+      if sys_desc.blank? || sys_desc.to_s == 'Null'
+        vprint_error("#{peer} No sysDescr received")
+        return
       end
+      sys_desc = sys_desc.split(/[\r\n]/).join(' ')
 
-      disconnect_snmp
+      sys_desc_map = {
+        /Windows/ => '1.3.6.1.4.1.77.1.2.25',
+        /Sun/ => '1.3.6.1.4.1.42.3.12.1.8'
+      }
+
+      matching_oids = sys_desc_map.select { |re, _| sys_desc =~ re }.values
+      if matching_oids.empty?
+        vprint_warning("#{peer} Skipping unsupported sysDescr: '#{sys_desc}'")
+        return
+      end
+      users = []
+
+      matching_oids.each do |oid|
+        snmp.walk(oid) do |row|
+          row.each { |val| users << val.value.to_s }
+        end
+      end
+      unless users.empty?
+        users.sort!
+        users.uniq!
+        print_good("#{peer} Found #{users.size} users: #{users.join(', ')}")
+      end
 
       report_note(
-        :host => rhost,
-        :port => datastore['RPORT'],
-        :proto => 'udp',
-        :sname => 'snmp',
-        :update => :unique_data,
-        :type => 'snmp.users',
-        :data => @users
+        host: rhost,
+        port: rport,
+        proto: 'udp',
+        sname: 'snmp',
+        update: :unique_data,
+        type: 'snmp.users',
+        data: users
       )
-
-
-    rescue ::SNMP::UnsupportedVersion
-    rescue ::SNMP::RequestTimeout
-    rescue ::Interrupt
-      raise $!
-    rescue ::Exception => e
-      print_error("Unknown error: #{e.class} #{e}")
+    rescue ::SNMP::RequestTimeout, ::SNMP::UnsupportedVersion
+      # too noisy for a scanner
+    ensure
+      disconnect_snmp
     end
-
   end
-
 end